BACKGROUND AND PURPOSE: For detecting therapeutic effect and matching of treatment groups in stroke trials, a scale that meets the clinimetric criteria is of the utmost importance. METHODS: The European Stroke Scale consists of 14 items selected for their specificity and their prognostic value. It is designed for patients with middle cerebral artery stroke. Interrater reliability, internal consistency, and time for completion were investigated in 74 patients. Intrarater reliability was studied in 38 patients. To establish concurrent validity, two trials were performed in 20 and 44 patients. The scale was correlated with the MCA Neurological Scale, the Canadian Stroke Scale, the Scandinavian Stroke Scale, the Barthel Index, and the Rankin Scale. Correlations were calculated by means of Spearman's correlation coefficient. The trial in 44 patients also investigated the prognostic validity of the scale for 1-month and 8-month neurological, functional, and handicap status. These data were analyzed by linear regression. RESULTS: Interrater (kappa value range, 0.62 to 0.85) and intrarater (kappa value range, 0.65 to 1.00) reliability for each item was good, and internal consistency was excellent (Cronbach's alpha coefficient, 0.92). Mean time for completion was 8.2 minutes (range, 4 to 14 minutes). Correlations of the European Stroke Scale with other neurological scales ranged from 0.93 to 0.95. The correlation with the Barthel Index and the Rankin Scale was 0.84 and -0.86. The R2 values for prognostic validity ranged from 0.45 to 0.81 (P < or = .0001). CONCLUSIONS: The European Stroke Scale has been developed according to the clinimetric criteria.